There have been many attempts to achieve an insulating material having down-like qualities for use in insulating articles such as clothing, sleeping bags, comforters, and the like. Prior efforts to develop a feasible material have most often yielded those that are too heavy and dense to be considered down-like.
An exception to this is for example, U.S. Pat. No. 4,588,635 to Donovan which discloses a superior synthetic down and has particular reference to light-weight thermal insulation systems which can be achieved by the use of fine fibers in low density assemblies and describes a range of fiber mixtures, that, when used to fabricate an insulating batt, provides advantageous, down-like qualities such as a high warmth-to-weight ratio, a soft hand, and good compression recovery. This material approaches, and in some cases might even exceed the thermal insulating properties of natural down. From a mechanical standpoint, however extremely fine fibers suffer from deficiencies of rigidity and strength that make them difficult to produce, manipulate and use. Recovery properties of such a synthetic insulator material are enhanced by larger fiber diameters, but an increase in the large fiber component will seriously reduce the thermal insulating properties overall. The problems associated with mechanical stability of fine fiber assemblies are exacerbated in the wet condition since surface tension forces associated with the presence of capillary water are considerably greater than those due to gravitational forces or other normal use loading and they have a much more deleterious effect on the structure. However, unlike waterfowl down, the disclosed fiber combination described provides excellent resistance to wetting.
Another exception is U.S. Pat. No. 4,992,327 to Donovan et al. which discloses the use of binder fiber components to improve insulator integrity without compromising desired attributes. More specifically the invention disclosed therein relates to synthetic fiber thermal insulator material in the form of a cohesive fiber structure, which structure comprises an assemblage of: (a) from 70 to 95 weight percent of synthetic polymeric microfibers having a diameter of from 3 to 12 microns; and (b) from 5 to 30 weight percent of synthetic polymeric macrofibers having a diameter of 12 to 50 microns, characterized in that at least some of the fibers are bonded at their contact points, the bonding being such that the density of the resultant structure is within the range 3 to 16 kg/m.sup.3, the thermal insulating properties of the bonded assemblage being equal to or not substantially less than the thermal insulating properties of a comparable unbonded assemblage. The reference also describes a down-like cluster form of the preferred fiber blends. The distinct performance advantages of the cluster form over the batt form are also disclosed in the patent.
However, these prior art clusters often were generally hand fabricated in a slow, tedious, batch process. Furthermore, the prior art materials were not easily blowable materials which could be used with conventional manufacturing equipment. Therefore there was a need for a blowable material which may be used as a partial or full replacement for down which may be manufactured and blown using conventional equipment.
In part as a result of need, them was developed blowable insulation clusters as described in U.S. Pat. No 6 ,329,051. The '051 patent described bowable clusters made from shredded banded batt or bonded web. The web or batt was described as the same fiber blend described in the '327 patent to Donovan. By shredding the batt or web formed of the materials described in the '327 patent the clusters were found to achieve down-like qualities including loft and insulating properties. Such clusters, in an admixture with natural material, is described in U.S. Pat. No. 6,329,052. Note, the disclosure of the aforementioned patents are incorporated fully herein by reference.
Another example is disclosed in U.S. Pat. No. 7,790,639, which relates to blowable insulative materials made from natural fibers and mixtures.
While the above mentioned blowable insulation materials are easily blowable with conventional blowers and can be used as a partial or full replacement for down or down-like insulative materials, they, however, have problems associated with weight and laundrability when not used properly. These materials could get wet during laundering and can permanently lose their insulative properties due to clumping. The blowable insulation clusters of the '051 and '052 patents incorporate only synthetic fibers. In contrast, the present invention is directed to provide blowable insulation material being made of natural fibers and short cut synthetic fibers.